NFPA 20: Type of valve at test connection on sensing lines

[IceYogurt]

Hi Engineers. I am asking for advise about the valve type at test connection on pressure-sensing lines. Further to NFPA 20 EDITION 2019 A.4.32(a), it marks the valve as globe valve. However, I cannot understand why it has to be globe rather than ball or gate.

I have three doubts, maybe four:
1. Does it have to globe valve and why?
2. Does it have to be UL/FM listed?
3. If yes, is there any notable brand can provide the half inch valves with UL/FM?

 

[LCREP]

This has been in NFPA 20 for a long time, at least since 1979 when I started in the insurance business in the USA. Why the NFPA 20 committee went this way I have no idea but I have tested 1000’s over the years never had a problem. If this job is in the USA you better follow what is required or perhaps the AHJ will not accept the installation.

 

[EvanVanVan]

I think it explains in the appendix (or the handbook) globe valves are required for their ability to gradually drop the pressure to get an accurate reading when the pump starts. It's more difficult to get an accurate reading with 1/4 turn ball valves where the pressure drops quickly. That being said, ball valves on sensing lines are very common and I doubt ul/fm listings has much to do with it.

 

[UFT12]

I ve seen many installations with ball valves and no, they don't have to be listed since the function of the system is not depended on them in case of malfunction.